1. Technical Field
The present invention pertains to surgical drapes for use with thermal treatment systems, such as the types of thermal treatment systems disclosed in: U.S. Pat. Nos. 4,393,659 (Keyes et al.), 4,934,152 (Templeton), 5,163,299 (Faries, Jr. et al.), 5,331,820 (Faries, Jr. et al.), 5,333,326 (Faries, Jr. et al.), 5,400,616 (Faries, Jr. et al.), 5,402,644 (Faries, Jr. et al.), 5,429,801 (Faries Jr. et al.), 5,457,962 (Faries, Jr. et al.), 5,502,980 (Faries, Jr. et al.), 5,522,095 (Faries, Jr. et al.), 5,524,643 (Faries, Jr. et al.), 5,551,240 (Faries, Jr. et al.), 5,615,423 (Faries, Jr. et al.), 5,653,938 (Faries, Jr. et al.), 5,809,788 (Faries, Jr. et al.), 5,816,252 (Faries, Jr. et al.), 5,857,467 (Faries, Jr. et al.), 5,862,672 (Faries, Jr. et al.), 5,879,621 (Faries, Jr. et al.), 5,950,438 (Faries, Jr. et al.), 6,003,328 (Faries, Jr. et al.), 6,035,855 (Faries, Jr. et al.), 6,087,636 (Faries, Jr. et al.), 6,091,058 (Faries, Jr. et al.), 6,255,627 (Faries, Jr. et al.), 6,371,121 (Faries, Jr. et al.) and 6,810,881 (Faries, Jr. et al.); and U.S. Patent Application Publication Nos. 2004/0200483 (Faries, Jr. et al.), 2004/0200480 (Faries, Jr. et al.), 2003/0231990 (Faries, Jr. et al.) and 2003/0172937 (Faries, Jr. et al.). The disclosures in the above-mentioned patents and patent application publications are incorporated herein by reference in their entireties.
2. Discussion of the Related Art
The above-referenced Keyes et al. patent (U.S. Pat. No. 4,393,659) discloses a surgical slush producing system having a cabinet with a heat transfer basin at its top surface. A refrigeration mechanism in the cabinet takes the form of a closed refrigeration loop including: an evaporator in heat exchange relation to the outside surface of the heat transfer basin; a compressor; a condenser; and a refrigeration expansion control, all located within the cabinet. A separate product basin is configured to be removably received in the heat transfer basin. Spacers, in the form of short cylindrical stubs or buttons, are arranged in three groups spaced about the heat transfer basin and projecting into the heat transfer basin interior to maintain a prescribed space between the two basins. During use, that space contains a thermal transfer liquid, such as alcohol or glycol, serving as a thermal transfer medium between the two basins. A sterile drape, impervious to the thermal transfer medium, is disposed between the product basin exterior and the liquid thermal transfer medium to preserve the sterile nature of the product basin. Surgically sterile liquid, such as sodium chloride solution, is placed in the product basin and congeals on the side of that basin when the refrigeration unit is activated. A scraping tool is utilized to remove congealed sterile material from the product basin side to thereby form a slush of desired consistency within the product basin. Some users of the system employ the scraping tool to chip the solid pieces from the basin side.
As noted in the above-referenced Templeton patent (U.S. Pat. No. 4,934,152), the Keyes et al. system has a number of disadvantages. In particular, the separate product basin must be removed and re-sterilized after each use. Additionally, the glycol or other thermal transfer medium is highly flammable or toxic and, in any event, complicates the procedure. The Templeton patent (U.S. Pat. No. 4,934,152) discloses a solution to these problems by constructing an entirely new apparatus whereby the product basin is eliminated in favor of a sterile drape impervious to the sterile surgical liquid, the drape being made to conform to the basin and directly receive the sterile liquid. Congealed liquid is scraped or chipped from the sides of the conformed drape receptacle to form the desired surgical slush.
The Faries, Jr. et al. patent (U.S. Pat. No. 5,163,299) notes that scraping congealed liquid from the drape is undesirable in view of the potential for damage to the drape, resulting in a compromise of sterile conditions. As a solution to the problem, the Faries, Jr. et al. patent (U.S. Pat. No. 5,163,299) proposes that the drape be lifted or otherwise manipulated by hand to break up the congealed liquid adhering to the drape. Although this hand manipulation is somewhat effective, it is not optimal, and often is inconvenient and constitutes an additional chore for operating room personnel.
Accordingly, several of the Faries, Jr. et al. patents (e.g., U.S. Pat. Nos. 5,331,820; 5,400,616; 5,457,962; 5,502,980; 5,653,938; 5,809,788; 5,857,467; 5,950,438; 6,003,328; and 6,035,855) resolve the problem of manual drape manipulation by disclosing various techniques and/or dislodgment mechanisms to automatically remove the congealed liquid adhering to the drape without endangering the integrity of the drape. For example, U.S. Pat. No. 5,331,820 addresses the problem of removing congealed frozen sterile medium from the sides of a sterile drape container in a surgical slush machine. Specifically, the sterile drape container is conformed to a cooled basin to establish a sterile field above the basin. The drape container collects a frozen sterile medium (e.g., saline) in a sterile slush-like consistency. The frozen medium tends to attach to the sides of the drape container in large clumps or pieces rather than automatically collecting within the container interior. The patent (U.S. Pat. No. 5,331,820) discloses a technique for automatically manipulating the drape relative to the basin wall to thereby cause the frozen congealed medium to detach from the drape sides and collect interiorly as the desired slush. Some of the embodiments disclosed in the patent (U.S. Pat. No. 5,331,820) cyclically move a plate or disk disposed between the drape and basin to manipulate the drape. The disk is described as being either secured to a movable machine or secured directly to the drape.
Since it has been found that, for many applications, it is more convenient to have the plate or disk secured directly to the drape, some of the aforementioned Faries, Jr. et al. patents (e.g., U.S. Pat. Nos. 5,457,962 and 5,502,980) disclose a disk or plate bonded to the underside of a sterile drape. The disk is provided with a fitting suitable for engaging a cyclically movable member to permit the disk to be cyclically moved in a manner to separate the drape container sides from the basin and cause frozen congealed pieces of sterile medium to fall into a slush pile.
In addition, when insignificant amounts of liquid are present within a thermal treatment system basin, the system cooling mechanism operates with minimal thermal resistance, thereby enabling the mechanism to become damaged. Further, the drapes employed by the system may be damaged by being disposed proximate the cooling mechanism without having the liquid to absorb the thermal energy. Since only sterile drapes are to be used during surgical procedures, a leak in a surgical drape compromises sterility and contaminates the entire surgical procedure, thereby increasing the risk of injury to a patient.
The related art has attempted to overcome this problem by employing sensing devices with surgical drapes. For example, U.S. Pat. No. 6,102,044 (Naidyhorski) discloses an electrode carrying surgical drape including a polymeric film having opposing surfaces and an electrode receiving aperture therethrough. An electrode is disposed through the aperture, while patches sealingly affix electrode portions to each of the opposing surfaces of the polymeric film in the vicinity of the aperture to form a reinforced laminated structure capable of maintaining the sterility of an established sterile field.
U.S. Pat. No. 6,810,881 (Faries, Jr. et al.) discloses a drape including a sensing device and disposed over a thermal treatment system having a basin recessed therein to form a drape container or receptacle within the basin for collecting a sterile medium. The thermal treatment system may either heat or congeal the sterile medium. The sensing device is typically disposed through the drape to provide a signal indicating the presence of liquid and/or leaks within the drape container to the system to facilitate control of system operation. In addition, the sensing device may be affixed to a plural basin drape utilized for a multiple basin thermal treatment system. The drape forms a drape receptacle within each basin, while a sensing device is typically disposed within each drape receptacle to detect the presence of liquid and/or a leak within that drape receptacle to facilitate control of system operation in substantially the same manner described above.
The above-described drapes can stand some improvement. In particular, the disk drape of the Faries, Jr. et al. patents (e.g., U.S. Pat. Nos. 5,457,962 and 5,502,980) preferably employs the disk on the underside of the drape. This requires medical personnel to manipulate the disk through the drape from the top or sterile drape surface in order to position the disk on the dislodgment mechanism and maintain drape sterility, thereby complicating placement of the disk on the dislodgment mechanism. Further, the above-described sensor drapes tend to subject the sensor or electrodes to accidental damage during stirring of solution within the basin by medical personnel. Moreover, the sensors tend to provide false readings in response to conductive objects placed within the basin in contact with the sensors. In order to protect the sensor and/or insulate the sensor from objects placed in a basin, a protective sleeve is generally employed, thereby increasing drape materials and costs.